'GAVEST thou the goodly wings unto the peacocks? or wings and
feathers unto the ostrich? which leaveth her eggs in the earth, and
warmeth them in dust, and forgetteth that the foot may crush them, or
that the wild beast may break them….Because God hath deprived her of
wisdom, neither hath He imparted to her understanding.'

This is the oldest theory of instinct. The writer of that sublime
monument of literary power in which it occurs observed a failure of
instinct on the part of the ostrich, and forthwith attributed the fact
to neglect on the part of the Deity; the implication plainly being that
in all cases where instinct is perfect, or completely suited to the
needs of the animal presenting it, the fact is to be attributed to a
God-given faculty of wisdom. This, I say, is the oldest theory of
instinct, and I may add that until within the past twenty-five years it
has
been the only theory of instinct, I think, therefore, I ought to begin
by explaining that this venerable and time-honoured theory is a purely
theological explanation of the ultimate source of instinct, and
therefore cannot be affected by any scientific theory as to the
proximate causes of instinct. It is with such a theory alone that we
shall here be concerned. 'When giants build, men must bring the
stones.' For the past eight or ten years I have been engaged in
elaborating Mr. Darwin's theories in the domain of psychology, and I
cannot allude to my own work in this connection without expressing the
deep obligations under which I lie to his ever ready and ever generous
assistance—assistance rendered not only in the way of conversation and
correspondence, but also by his kindness in making over to me all his
unpublished manuscripts, together with the notes and clippings which he
had been making for the past forty years in psychological matters. I
have now gone carefully through all this material, and have published
most of it in my work on 'Mutual Evolution in Animals.' I allude to
this work on the present occasion in order to observe that, as it has
so recently come out, I shall feel myself entitled to assume that few
have read it; and therefore I shall not cramp my remarks by seeking to
avoid any of the facts or arguments therein contained.

As there are not many words within the compass of our language which
have had their meanings less definitely fixed than the word 'instinct,'
it is necessary that I should begin by clearly defining the sense in
which I shall use it.

In general literature and conversation we usually find that instinct
is antithetically opposed to reason, and this in such wise that the
mental operations of the lower animals are termed instinctive; those of
man are termed rational. This rough and ready attempt at psychological
classification has descended to us from remote antiquity, and, like
kindred attempts at zoological classification, is not a bad one so far
as it goes. To divide the animal kingdom into beasts, fowls, fish, and
creeping things, is a truly scientific classification as far as it
goes, only it does not go far enough for the requirements of more
careful observation; that is to say, it only recognises the more
obvious and sometimes only superficial differences, while it neglects
the more hidden and usually more important resemblances. And to
classify all the mental phenomena of animal life under the term
'instinct,' while reserving the term 'reason' to designate a mental
peculiarity distinctive of man, is to follow a similarly archaic
method. It is quite true that instinct preponderates in animals, while
reason preponderates in man. This obvious fact is what the world has
always seen, just as it saw that flying appeared to be distinctive of
birds, and creeping of reptiles. Nevertheless, a bat was all the while
a mammal and a pterodactyl was not a bird; and it admits of proof as
definite that what we call instinct in animals occurs in man, and that
what we call reason in man occurs in animals. This, I mean, is the case
if we wait to attach any definition to the words which we employ. It is
quite evident that there is some difference between the mind of a man
and the mind of a brute, and if without waiting to ascertain what this
difference is, we say that it consists in the presence or absence of
the faculty of reason, we are making the same kind of mistake as when
we say that the difference between a bird and a mammal consists in the
presence or absence of the faculty of flying. Of course, if we choose,
we may employ the word 'reason' to signify all the differences taken
together, whatever they may be; and so, if we like, we may use the word
'flying.' But in either case we shall be talking nonsense, because we
should be divesting the words of their meaning, or proper sense. The
meaning of the word 'reason' is the faculty of ratiocination—the
faculty of drawing inferences from a perceived equivalency of
relations, no matter whether the relations involve the simplest mental
perceptions, or the most abstruse mathematical calculations. And in
this, the only real and proper sense of the word, reason is not the
special prerogative of man, but occurs through the zoological scale at
least as far down as the articulata.

First of all, instinct involves mental operation, and
therefore implies consciousness. This is the point which distinguishes
instinct from reflex action. Unless we assume that a new-born infant,
for example, is conscious of sucking, it is as great a misnomer to term
its adaptive movements in the performance of this act instinctive, as
it would be similarly to term the adaptive movements of its stomach
subsequently performing the act of digestion.

Next, instinct implies hereditary knowledge of the objects and
relations with respect to which it is exercised; it may therefore
operate in full perfection prior to any experience on the part of the
individual. When the pupa of a bee, for instance, changes into an
imago, it passes suddenly from one set of experiences to another, the
difference between its previous life as a larva and its new life as an
imago being as great as the difference between the lives of two animals
belonging to two different sub-kingdoms; yet as soon as its wings are
dry it exhibits all the complex instincts of the mature insect in full
perfection. And the same is true of the instincts of vertebrated
animals, as we know from the researches of the late Mr. Douglas
Spalding and others.

Again, instinct does not imply any necessary knowledge of the
relations between means employed and ends attained. Such knowledge may
be present in any degree of distinctness, or it may not be present at
all; but in any case it is immaterial to the exercise of the instinct.
Take, for example, the instinct of the Banbex. This insect brings from
time to time fresh food to her young, and remembers very exactly the
entrance to her cell, although she has covered it with sand, so as not
to be distinguishable from the surrounding surface. Yet M. Fabre found
that if he brushed away the earth and the underground passage leading
to the nursery, thus exposing the contained larva, the parent insect
'was quite at a loss, and did not even recognise her own offspring. It
seemed as if she knew the doors, nursery, and the passage, but not her
child.'

Lastly, instinct is always similarly manifested under similar
circumstances by all the individuals of the same species. And, it may
be added, these circumstances are always such as have been of frequent
occurrence in the life-history of the species.

Now in all these respects instinct differs conspicuously from every
other faculty of mind, and especially from reason. Therefore, to gather
up all these differentiæ into one definition, we may say that
instinct is the name given to those faculties of mind which are
concerned in consciously adaptive action, prior to individual
experience, without necessary knowledge of the relation between means
employed and ends attained; but similarly performed under similar and
frequently recurring circumstances by all the individuals of the same
species.

consider Mr. Darwin's theory of the origin and development of
instincts.

Now, to begin with, Mr. Darwin's theory does not, as many suppose
that it does, ascribe the origin and development of all instincts to
natural selection. This theory does, indeed, suppose that natural
selection is an important factor in the process; but it neither
supposes that it is the only factor, nor even that in the case of
numberless instincts it has had anything at all to do with their
formation. Take, for example, the instinct of wildness, or of
hereditary fear as directed towards any particular enemy—say man. It
has been the experience of travellers who have first visited oceanic
islands without human inhabitants and previously unvisited by man, that
the animals are destitute of any fear of man. Under such circumstances
the birds have been known to alight on the heads and shoulders of the
newcomers, and wolves to come and eat meat held in one hand while a
knife was held ready to slay them with the other. But this primitive
fearlessness of man gradually passes into an hereditary instinct of
wildness, as the special experiences of man's proclivities accumulate;
and as this instinct is of too rapid a growth to admit of our
attributing it to natural selection (not one per cent. of the animals
having been destroyed before the instinct is developed), we can only
attribute its growth to the effects of inherited observation. In other
words, just as in the lifetime of the individual, adjustive actions
which were originally intelligent may by frequent repetition become
automatic, so in the lifetime of the species, actions originally
intelligent may, by frequent repetition and heredity, so unite their
efforts on the nervous system that the latter is prepared, even before
individual experience, to perform adjustive actions mechanically which,
in previous generations, were performed intelligently. This mode of
origin of instincts has been appropriately called the 'lapsing of
intelligence,' and it was fully recognised by Mr. Darwin as a factor in
the formation of instinct.

The Darwinian theory of instinct, then, attributes the evolution of
instincts to these two causes acting either singly or in
combination—natural selection and lapsing intelligence. I shall now
proceed to adduce some of the more important facts and considerations
which, to the best of my judgment, support this theory, and show it to
be by far the most comprehensive and satisfactory explanation of the
phenomena which has hitherto been propounded.

That many instincts must have owed their origin and development to
natural selection exclusively is, I think, rendered evident by the
following general considerations:—

(1) Considering the great importance of instincts to species, we are
prepared to expect that they must be in large part subject to the
influence of natural selection. (2) Many instinctive actions are
performed by animals too low in the scale to admit of our supposing
that the adjustments which are now instinctive can ever have been

intelligent. (3) Among the higher animals instinctive actions are
performed at an age before intelligence, or the power of learning by
individual experience, has begun to assert itself. (4) Many instincts,
as we now find them, are of a kind which, although performed by
intelligent animals at a matured age, yet can obviously never have been
originated by intelligent observation. Take, for instance, the instinct
of incubation. It is quite impossible that any animal can ever have
kept its eggs warm with the intelligent purpose of developing their
contents; so we can only suppose that the incubating instinct began in
some such form as we now see it in the spider, where the object of the
process is protection, as distinguished from the imparting of heat. But
incidental to such protection is the imparting of heat, and as animals
gradually became warm-blooded, no doubt this latter function became of
more and more importance to incubation. Consequently, those individuals
which most constantly cuddled their eggs would develop most progeny,
and so the incubating instinct would be developed by natural selection
without there ever having been any intelligence in the matter.

From these four general considerations, therefore, we may conclude
(without waiting to give special illustrations of each) that one mode
of origin of instincts consists in natural selection, or survival of
the fittest, continuously preserving actions which, although never
intelligent, yet happen to have been of benefit to the animals which
first chanced to perform them. Among animals, both in a state of nature
and domestication, we constantly meet with individual peculiarities of
disposition and of habit, which in themselves are utterly meaningless,
and therefore quite useless. But it is easy to see that if among a
number of such meaningless or fortuitous psychological variations, any
one arises which happens to be of use, this variation would be seized
upon, intensified, and forced by natural selection, just as in the
analogous case of structures. Moreover there is evidence that such
fortuitous variations in the psychology of animals (whether useless or
accidentally useful) are frequently inherited, so as to become
distinctive not merely of individuals, but of races or strains. Thus,
among Mr. Darwin's manuscripts I find a letter from Mr. Thwaits under
the date 1860, saying that all his domestic ducks in Ceylon had quite
lost their natural instincts with regard to water, which they would
never enter unless driven, and that when the young birds were thus
compelled to enter the water they had to be quickly taken out again to
prevent them from drowning. Mr. Thwaits adds that this peculiarity only
occurs in one particular breed. Tumbler-pigeons instinctively tumbling,
pouter-pigeons instinctively pouting, &c., are further
illustrations of the same general fact.

Coming now to instincts developed by lapsing intelligence, I have
already alluded to the acquisition of an hereditary fear of man as an
instance of this class. Now not only may the hereditary fear of man

be thus acquired through the observation of ancestors—and this even
to the extent of knowing by instinct what constitutes safe distance
from fire-arms; but, conversely, when fully formed it may again be lost
by disuse. Thus there is no animal more wild, or difficult to tame,
than the young of the wild rabbit; while there is no animal more tame
than the young of the domestic rabbit. And the same remark applies,
though in a somewhat lesser degree, to the young of the wild and of the
domestic duck. For, according to Dr. Rae, 'If the eggs of a wild duck
are placed with those of a tame duck under a hen to be hatched, the
ducklings from the former, on the very day they leave the egg, will
immediately endeavour to hide themselves, or take to the water, if
there be any water, should anyone approach, whilst the young from the
tame duck's eggs will show little or no alarm.' Now, as neither rabbits
nor ducks are likely to have been selected by man to breed from on
account of tameness, we may set down the loss of wildness in the
domestic breeds to the uncompounded effects of hereditary memory of man
as a harmless animal, just as we attributed the original acquisition of
instinctive wildness to the hereditary memory of man as a dangerous
animal; in neither case can we suppose that the principle of selection
has operated in any considerable degree.

Thus far, for the sake of clearness, I have dealt separately with
these two factors in the formation of instinct—natural selection and
lapsing intelligence—and have sought to show that either of them
working singly is sufficient to develop some instincts. But, no doubt,
in the case of most instincts intelligence and natural selection have
gone hand-in-hand, or co-operated, in producing the observed
results—natural selection always securing and rendering permanent any
advances which intelligence may have made. Thus, to take one case as an
illustration. Dr. Rae tells me that the grouse of North America have
the curious instinct of burrowing a tunnel just below the surface of
the snow. In the end of this tunnel they sleep securely, for when any
four-footed enemy approaches the mouth of the tunnel, the bird, in
order to escape, has only to fly up through the thin covering of snow.
Now in this case the grouse probably began to burrow in the snow for
the sake of warmth, or concealment, or both; and, if so, thus far the
burrowing was an act of intelligence. But the longer the tunnel the
better would it serve in the above-described means of escape; therefore
natural selection would tend to preserve the birds which made the
longest tunnels, until the utmost benefit that length of tunnel could
give had been attained.

And similarly, I believe, all the host of animal instincts may be
fully explained by the joint operation of these two causes—intelligent
adjustment and survival of the fittest. For now, I may draw attention
to another fact which is of great importance, viz., that instincts
admit of being modified as modifying circumstances may

require. In other words, instincts are not rigidly fixed, but are
plastic, and their plasticity renders them capable of improvement or of
alteration, according as intelligent observation requires. The
assistance which is thus rendered by intelligence to natural selection
must obviously be very great, for under any change in the surrounding
conditions of life which calls for a corresponding change in the
ancestral instincts of the animal, natural selection is not left to
wait, as it were, for the required variations to arise fortuitously;
but is from the first furnished by the intelligence of the animal with
the particular variations which are needed.

In order to demonstrate this principle of the variation of instinct
under the guidance of intelligence, I may here introduce a few examples.

Huber observes, 'How ductile is the instinct of bees, and how
readily it adapts itself to the place, the circumstances, and the needs
of the community.' Thus, by means of contrivances, which I need not
here explain, he forced the bees either to cease building combs, to
change their instinctive mode of building from above downwards, to
building in the reverse direction, and also horizontally. The bees in
each case changed their mode of building accordingly. Again, an
irregular piece of comb, when placed by Huber on a smooth table,
tottered so much that the bumble bees could not work on so unsteady a
basis. To prevent the tottering, two or three bees held the comb by
fixing their front feet on the table, and their hind feet on the comb.
This they continued to do, relieving guard, for three days, until they
had built supporting pillars of wax. Some other bumble bees, when shut
up, and so prevented from getting moss wherewith to cover their nests,
tore threads from a piece of cloth, and 'carded them with their feet
into a fretted mass,' which they used as moss. Lastly, Andrew Knight
observed that his bees availed themselves of a kind of cement made of
iron and turpentine, with which he had covered some decorticated
trees—using this ready-made material instead of their own propolis, the
manufacture of which they discontinued; and more recently it has been
observed that bees, 'instead of searching for pollen, will gladly avail
themselves of a very different substance, namely, oatmeal.' Now in all
these cases it is evident that if, from any change of environment, such
accidental conditions were to occur in a state of nature, the bees
would be ready at any time to meet them by intelligent adjustment,
which, if continued sufficiently long and aided by selection, would
pass into true instincts of building combs in new directions, of
supporting combs during their construction, of carding threads of
cloth, of substituting cement for propolis, and of oatmeal for pollen.

Turning to higher animals, Andrew Knight tells us of a bird which,
having built her nest upon a forcing-house, ceased to visit it during
the day when the heat of the house was sufficient to incubate

the eggs; but always returned to sit upon the eggs at night when the
temperature of the house fell, Again, thread and worsted are now
habitually used by sundry species of birds in building their nests,
instead of wool and horse-hair, which in turn were no doubt originally
substitutes for vegetable fibres and grasses. This is especially
noticeable in the case of the tailor-bird, which finds thread the best
material wherewith to sew. The common house-sparrow furnishes another
instance of intelligent adaptation of nest-building to circumstances;
for in trees it builds a domed nest (presumably, therefore, the
ancestral type), but in towns avails itself by preference of sheltered
holes in buildings, where it can afford to save time and trouble by
constructing a loosely formed nest. Moreover, the chimney- and
house-swallows have similarly changed their instincts of nidification,
and in America this change has taken place within the last two or three
hundred years. Indeed, according to Captain Elliott Coues, all the
species of swallow on that continent (with one possible exception) have
thus modified the sites and structures of their nests in accordance
with the novel facilities afforded by the settlement of the country.

Another instructive case of an intelligent change of instinct in
connection with nest-building is given from a letter by Mr. Haust,
dated New Zealand, 1862, which I find among Mr. Darwin's manuscripts.
Mr. Haust says that the Paradise duck, which naturally or usually
builds its nest along the rivers on the ground, has been observed by
him on the east of the island, when disturbed in their nests upon the
ground, to build 'new ones on the tops of high trees, afterwards
bringing their young ones down on their backs to the water;' and
exactly the same thing has been recorded by another observer of the
wild ducks of Guiana. Now if intelligent adjustment to peculiar
circumstances is thus adequate, not only to make a whole breed or
species of bird transport their young upon their backs—or, as in the
case of the woodcock, between their legs—but even to make web-footed
water-fowl build their nests in high trees, I think we can have no
doubt that if the need of such adjustment were of sufficiently long
continuance, the intelligence which leads to it would eventually
produce a new and remarkable modification of their ancestral instinct
of nest-building.

Turning now from the instinct of modification to that of incubation,
I may give one example to show the plasticity of the instinct in
relation to the observed requirements of progeny. Several years ago I
placed in the nest of a sitting Brahma hen, four newly-born ferrets.
She took to them almost immediately, and remained with them for rather
more than a fortnight, when I made a separation. During the whole of
the time the hen had to sit upon the nest, for the young ferrets were
not able to follow her about, as young chickens would have done. The
hen was very much puzzled by the lethargy of her

offspring, and two or three times a day she used to fly off the nest
calling on her brood to follow; but, on hearing their cries of distress
from cold, she always returned immediately, and sat with patience for
six or seven hours more. I found that it only took the hen one day to
learn the meaning of their cries of distress; for after the first day
she would always run in an agitated manner to any place where I
concealed the ferrets, provided that this place was not too far away
from the nest to prevent her from hearing the cries of distress. Yet I
do not think it would be possible to imagine a greater contrast between
two cries than the shrill piping note of a young chicken, and the
hoarse growling noise of a young ferret. At times the hen used to fly
off the nest with a loud scream, which was doubtless due to the
unaccustomed sensation of being gripped by the young ferrets in their
search for the teats. It is further worthy of remark that the hen
showed so much anxiety when the ferrets were taken from the nest to be
fed, that I adopted the plan of giving them the milk in their nest, and
with this arrangement the hen seemed quite satisfied; at any rate she
used to chuck when she saw the milk coming, and surveyed the feeding
with evident satisfaction.

Thus we see that even the oldest and most important of instincts in
bees and birds admit of being greatly modified, both in the individual
and in the race, by intelligent adaptation to changed conditions of
life; and therefore we can scarcely doubt that the principle of lapsing
intelligence must be of much assistance to that of natural selection in
the origination and development of instincts.

I shall now turn to another branch of the subject. From the nature
of the case it is not to be expected that we should obtain a great
variety of instances among wild animals of new instincts acquired under
human observation, seeing that the conditions of their life, as a rule,
remain pretty uniform for any periods over which human observation can
extend. But from a time before the beginning of history, mankind, in
the practice of domesticating animals, has been making what we may deem
a gigantic experiment upon the topic before us.

The influences of domestication upon the psychology of animals may
be broadly considered as both negative and positive—negative in the
obliteration of natural instincts; positive in the creation of
artificial instincts. We will consider these two branches separately.
Here we may again revert to the obliteration of natural wildness. We
all know that the horse is an easily breakable animal, but his nearest
allies in a state of nature, the zebra and the quagga, are the most
obstinately unbreakable of animals. Similar remarks apply to the
natural wildness of all wild species of kine, as contrasted with the
innate tameness of our domesticated breeds. Consider again the case of
the cat. The domesticated animal is sufficiently tame, even from
kittenhood, whereas its nearest cousin in a state of nature, the wild
cat, is perhaps of all animals the most untameable. But of course it is

in the case of the dog that we meet with the strongest evidence on
this point. The most general and characteristic features in the
psychology of all the domesticated varieties are faithfulness,
docility, and sense of dependence upon a master; whereas the most usual
and characteristic features in the psychology of all the wild species
are fierceness, treachery, and self-reliance. But, not further to
pursue the negative side of this subject, let us now turn to the
positive, or to the power which man has shown himself to possess of
implanting new instincts in the mental constitution of animals. For the
sake of brevity I shall here confine myself to the most conspicuous
instance, which is of course furnished by the dog, seeing that the dog
has always been selected and trained with more or less express
reference to his mental qualities. And here I may observe that in the
process of modifying psychology by domestication exactly the same
principles have been brought into operation as those to which we
attribute the modification of instincts in general; for the processes
of artificial selection and training in successive generations are
precisely analogous to the processes of natural selection and lapsing
of intelligence in a state of nature.

Touching what Mr. Darwin calls the artificial instincts of the dog,
I may first mention those which he has himself dilated upon—I mean the
instincts of pointing, retrieving, and sheep-tending; but as Mr. Darwin
has already fully treated of these instincts, I shall not go over the
ground which he has traversed, but shall confine myself to the
consideration of another artificial instinct, which, although not
mentioned by him, seems to me of no less significance—I mean the
instinct of guarding property. This is a purely artificial instinct,
created by man expressly for his own purposes: and it is now so
strongly ingrained in the intelligence of the dog that it is unusual to
find any individual animal in which it is wholly absent. Thus, we all
know, that without any training a dog will allow a stranger to pass by
his master's gate without molestation, but that as soon as the stranger
passes within the gate, and so trespasses upon what the dog knows to be
his master's territory, the animal immediately begins to bark in order
to give his master notice of the invasion. And this leads me to observe
that barking is itself an artificial instinct, developed, I believe, as
an offshoot from the more general instinct of guarding property. None
of the wild species of dog are known to bark, and therefore we must
conclude that barking is an artificial instinct, acquired for the
purpose of notifying to his master the presence of thieves or enemies.
I may further observe that this instinct of guarding property extends
to the formation of an instinctive idea on the part of the animal, of
itself constituting part of that property. If, for instance, a friend
gives you temporary charge of his dog, even although the dog may never
have seen you before, observing that you are his master's friend and
that his master intends

you to take charge of him, he immediately transfers his allegiance
from his master to you, as to a deputed owner, and will then follow you
through any number of crowded streets with the utmost confidence. Thus,
whether we look to the negative or to the positive influences of
domestication upon the psychology of the dog, we must conclude that a
change has been wrought, so profound that the whole mental constitution
of the animal now presents a more express reference to the needs of
another, and his enslaving animal, than it does to his own. Indeed, we
may say that there is no one feature in the whole psychology of the dog
which has been left unaltered by the influence of man, excepting only
those instincts which being neither useful nor harmful to man have
never been subject to his operation—such, for instance, as the instinct
of burying food, turning round to make a bed before lying down, &c.

I will now turn to another branch of the subject, and one which,
although in my opinion of the greatest importance, has never before
been alluded to; I mean the local and specific variations of instinct.
By a local variation of instinct, I mean a variation presented by a
species in a state of nature over some particular area of geographical
distribution. It is easy to see the importance of such local variations
of instinct as evidence of the transmutation of instinct, if we reflect
that such a local variation is obviously on its way to becoming a new
instinct. For example, the beavers in California have ceased to make
dams, the hyenas in South Africa have ceased to make burrows, and there
is a squirrel in the neighbourhood of Mount Airy which has developed
carnivorous tastes—running about the trees, not to search for nuts, but
to search for birds, the blood of which it sucks. In Ohinitahi there is
a mountain parrot which before the settlement of the place was a honey
eater, but when sheep were introduced the birds found that mutton was
more palatable to them than honey, and quickly abandoned their
ancestral habits, exchanging their simple tastes of honey eaters for
the savageness of tearers of flesh. For the birds come in flocks,
single out a sheep, tear out the wool, and when the sheep, exhausted by
running about, falls upon its side, they bore into the abdominal cavity
to get at the fat which surrounds the kidneys.

These, I think, are sufficient instances to show what I mean by
local variations of instinct. Turning now to the specific variations, I
think they constitute even stronger evidence of the transmutation of
instinct; for where we find an instinct peculiar to a species, or not
occurring in any other species of the genus, we have the strongest
possible evidence of that particular instinct having been specially
developed in that particular species. And this evidence is of
particular cogency when, as sometimes happens, the change of instinct
is associated with structures pointing to the state of the instincts
before the change. Thus, for example, the dipper belongs to a
non-aquatic

family of birds, but has developed the instinct, peculiar to its
species, of diving under water and running along the bottoms of
streams. The species, however, has not had time, since the acquisition
of this instinct, to develop any of the structures which in all aquatic
families of birds are correlated with their aquatic instincts, such as
webbed feet, &c. That is to say, the bird retains all its
structural affinities, while departing from the family type as regards
its instincts. A precisely converse case occurs in certain species of
birds belonging to families which are aquatic in their affinities,
these species, however, having lost their aquatic instincts. Such is
the case, for example, with the upland geese. These are true geese in
all their affinities, retaining the webbed feet, and all the structures
suited to the display of aquatic instincts; yet they never visit the
water. Similarly, there are species of parrots and tree frogs, which,
while still retaining the structures adapted to climbing trees, have
entirely lost their arboreal habits. Now, short of actual historical or
palæontological information—which of course in the case of instincts is
unattainable, seeing that instincts, unlike structures, never occur in
a fossil state—short, I say, of actual historical or palæontological
information, we could have no stronger testimony to the fact of
transmutation of instincts than is furnished by such cases, wherein a
particular species, while departing from the instinctive habits of its
nearest allies, still retains the structures which are only suited to
the instincts now obsolete.

Now this last head of evidence—that, namely, as to local and
specific variations of instincts—differs in one important respect from
all the other heads of evidence which I have previously adduced. For
while these other heads of evidence had reference to the theory
concerning the causes of transmutation, this head of evidence
has reference to the fact of transmutation. Whatever,
therefore, we may think concerning the evidence of the causes, this
evidence is quite distinct from that on which I now rely as conclusive
proof of the fact.

I shall now, for the sake of fairness, briefly allude to the more
important cases of special difficulty which lie against Mr. Darwin's
theory of the origin and development of instincts. For the sake of
brevity, however, I shall not allude to those cases of special
difficulty which he has himself treated in the 'Origin of Species,' but
shall confine myself to considering the other and most formidable cases
which, after surveying all the known instincts presented by animals, I
have felt to be such.

First, we have the alleged instinct of the scorpion committing
suicide when surrounded by fire. This instinct, if it really exists,
would no doubt present a difficulty, because it is clearly an instinct
which, being not only of no use, but actually detrimental both to the
individual and the species, could never have been developed either by
natural selection or by lapsing intelligence. I may, however, dismiss

this case with a mere mention, because as yet the evidence of the
fact is not sufficiently precise to admit of our definitely accepting
it as a fact.

There can be no such doubt, however, attaching to another instinct
largely prevalent among insects, and which is unquestionably
detrimental, both to the individual and to the species. I allude to
the instinct of flying through flame. This is unquestionably a true
instinct, because it is manifested by all individuals of the same
species. How then are we to explain its occurrence? I think we may do
so by considering, in the first place, that flame is not a sufficiently
common object in nature to lead to any express instinct for its
avoidance; and in the next place by considering that insects
unquestionably manifest a disposition to approach and examine shining
objects. Whether this disposition is due to mere curiosity, or to a
desire to ascertain if the shining objects will, like flowers, yield
them food, is a question which need not here concern us. We have merely
to deal with the fact that such a general disposition is displayed.
Taking then this fact, in connection with the fact that flame is not a
sufficiently common object in nature to lead to any instinct expressly
directed against its avoidance, it seems to me that the difficulty we
are considering is a difficulty no longer.

The shamming-dead of insects appears at first sight a formidable
difficulty, because it is impossible to understand how any insect can
have acquired the idea either of death or of its intentional
simulation. This difficulty occurred to Mr. Darwin thirty or forty
years ago, and among his manuscripts I find some very interesting notes
of experiments upon the subject. He procured a number of insects which
exhibited the instinct, and carefully noted the attitude in which they
feigned death. Some of these insects he then killed, and he found that
in no case did the attitude in which they feigned death resemble the
attitude in which they really died. Consequently we must conclude that
all the instinct amounts to is that of remaining motionless, and
therefore, inconspicuous, in the presence of danger; and there is no
more difficulty in understanding how such an instinct as this should be
developed by natural selection in an animal which has no great powers
of locomotion, than there is in understanding how the instinct to run
away from danger should be developed in another animal with powers of
rapid locomotion. The case, however, is not, I think, quite so easy to
understand in the feigning death of higher animals. From the evidence
which I have I find it almost impossible to doubt that certain birds,
foxes, wolves, and monkeys, not to mention some other and more doubtful
cases, exhibit the peculiarity of appearing dead when captured by man.
As all these animals are highly locomotive, we cannot here attribute
the fact to protective causes. Moreover, in these animals this
behaviour is not truly instinctive, inasmuch as it is not presented by
all, or even most individuals. As yet, however, observation of the
facts is insufficient to furnish any data as to their

explanation, although I may remark that possibly they may be due to
the occurrence of the mesmeric or hypnotic state, which we know from
recent researches may be induced in animals under the influence of
forcible manipulation.

The instinct of feigning injury by certain birds presents a peculiar
difficulty. As we all know, partridges, ducks, and plovers, when they
have a brood of young ones, and are alarmed by the approach of a
carnivorous quadruped, such as a dog, will pretend to be wounded,
flapping along the ground with an apparently broken wing in order to
induce the four-footed enemy to follow, and thus to give time for the
young brood to disperse and hide themselves. The difficulty here, of
course, is to understand how the birds can have acquired the idea of
pretending to have a broken wing, for the occasions must be very rare
on which any bird has seen a companion thus wounded followed by a
carnivorous quadruped; and even if such observations on their part were
of frequent occurrence, it would be difficult to accredit the animals
with so high a degree of reasoning power as would be required for them
intentionally to imitate such movements. When I consulted Mr. Darwin
with reference to this difficulty, he gave me a provisional hypothesis
by which it appeared to him that it might be met. He said that any one
might observe, when a hen has a brood of young chickens and is
threatened by a dog, that she will alternately rush at the dog and back
again to the chickens. Now if we could suppose that under these
circumstances the mother bird is sufficiently intelligent to observe
that when she runs away from the dog, she is followed by the dog, it is
not impossible that the maternal instinct might induce her to run away
from a brood in order to lead the dog away from it. If this happened in
any cases, natural selection would tend to preserve those mother birds
which adopted this device. I give this explanation as the only one
which either Mr. Darwin or myself has been able to suggest. It will be
observed, however, that it is unsatisfactory, inasmuch as it fails to
account for the most peculiar feature of the instinct—I mean the
trailing of the apparently wounded wing.

The instinct of migration furnishes another case of special
difficulty, but as I have no space to dwell upon the sundry questions
which it presents for solution, I shall now pass on to the last of the
special difficulties which most urgently call for consideration. The
case to which I refer deserves, I think, to be regarded as the most
extraordinary instinct in the world. There is a species of wasp-like
insect, called the Sphex. This insect lays its eggs in a hole excavated
in the ground. It then flies away and finds a spider, which it stings
in the main nerve-centre of the animal. This has the effect of
paralysing the spider without killing it. The sphex then carries the
now motionless spider to its nursery, and buries it with the eggs. When
the eggs hatch out the grubs feed on the paralysed prey, which is then
still

alive and therefore quite fresh, although it has never been able to
move since the time when it was buried. Of course the difficulty here
is to understand how the sphex insect can have acquired so much
anatomical and physiological knowledge concerning its prey as the facts
imply. We might indeed suppose, as I in the first instance was led to
suppose, that the sting of the sphex and the nerve-centre of the spider
being both organs situated on the median line of their respective
possessors, the striking of the nerve-centre by the sting might in the
first instance have been thus accidentally favoured, and so have
supplied a basis from which natural selection could work to the
perfecting of an instinct always to sting in one particular spot. But
more recently the French entomologist, M. Fabre, who first noticed
these facts with reference to the stinging of the spider, has observed
another species of sphex which preyed upon the grasshopper, and as the
nervous system of a grasshopper is more elongated than the nervous
system of a spider, the sphex in this case has to sting its prey in
three successive nerve-centres in order to induce paralysis. Again,
still more recently, M. Fabre has found another species of sphex, which
preys upon a caterpillar, and in this case the animal has to sting its
victim in nine successive nerve-centres. On my consulting Mr. Darwin in
reference to these astonishing facts, he wrote me the following letter:—

I have been thinking about Pompilius and its allies. Please take the
trouble to read on perforation of the corolla, by Bees, p. 425, of my
'Cross-fertilisation,' to end of chapter. Bees show so much intelligence in their acts, that it seems not improbable to me that the progenitors
of Pompilius originally stung caterpillars and spiders, &c., in any
part of their bodies, and then observed by their intelligence that if
they stung them in one particular place, as between certain segments on
the lower side, their prey was at once paralysed. It does not seem to
me at all incredible that this action should then become instinctive, i.e. memory transmitted from one generation to another. It does not seem
necessary to suppose that, when Pompilius stung its prey in the
ganglion it intended, or knew, that their prey would keep long alive.
The development of the larva may have been subsequently modified in
relation to their half dead, instead of wholly dead prey; supposing
that the prey was at first quite killed, which would have required much
stinging. Turn this over in your mind, &c.

I confess that this explanation does not appear to me altogether
satisfactory, although it is no doubt the best explanation that can be
furnished on the lines of Mr. Darwin's theory.

In the brief space at my disposal, I have endeavoured to give an
outline sketch of the main features of the evidence which tends to show
that animal instincts have been slowly evolved under the influence of
natural causes, the discovery of which we owe to the genius of Darwin.
And, following the example which he has set, I shall conclude by
briefly glancing at a topic of wider interest and more general
importance. The great chapter on Instinct in the Origin of Species is brought to a close in the following words:—

Finally it may not be a logical deduction, but to my imagination it
is far more satisfactory to look at such instincts as the young cuckoo
ejecting its foster-brothers, ants making slaves, the larvæ of
ichneumonidæ feeding within the live bodies of caterpillars, not as
specially endowed or created instincts, but as small consequences of
one general law leading to the advancement of all organic beings,
namely, multiply, vary, let the strongest live, and the weakest die.

This law may seem to some, as it has seemed to me, a hard one—hard,
I mean, as an answer to the question which most of us must at some time
and in some shape have had faith enough to ask, 'Shall not the Judge of
all the earth do right?' For this is a law, rigorous and universal,
that the race shall always be to the swift, the battle without fail to
the strong; and in announcing it the voice of science has proclaimed a
strangely new beatitude—Blessed are the fit, for they shall inherit the
earth. Surely these are hard sayings, for in the order of nature they
constitute might the only right. But if we are thus led to feel a sort
of moral repugnance to Darwinian teaching, let us conclude by looking
at this matter a little more closely, and in the light that Darwin
himself has flashed upon it in the short passage which I have quoted.

Eighteen centuries before the publication of this book—the 'Origin
of Species'—one of the founders of Christianity had said, in words as
strong as any that have been used by the Schopenhauers and Hartmanns of
to-day, 'the whole creation groaneth in pain and travail.' Therefore we
did not need a Darwin to show us this terrible truth; but we did need a
Darwin to show us that out of all the evil which we see at least so
much of good as we have known has come; that if this is a world of pain
and sorrow, hunger, strife and death, at least the suffering has not
been altogether profitless; that whatever may be 'the far-off divine
event to which the whole creation moves,' the whole creation, in all
its
pain and in all its travail, is certainly moving, and this in a
direction which makes, if not for 'righteousness,' at all events for
improvement. No doubt the origin of evil has proved a more difficult
problem to solve than the origin of species; but, thus viewed, I think
that the Darwinian doctrine deserves to be regarded as in some measure
a mitigation of the difficulty; certainly in no case an aggravation of
it. I do not deny that an immense residuum of difficulty remains,
seeing that, so far as we can judge, the means employed certainly do
not appear to be justified by the ends attained. But even here we ought
not to lose sight of the possibility that, if we could see deeper into
the mystery of things, we might find some further justification of the
evil, as unsuspected as was that which, as it seems to me, Darwin has
brought to light. It is not in itself impossible—perhaps it is not even
improbable—that the higher instincts of man may be pointing with as
true an aim as those lower instincts of the brutes which we have been
contemplating. And, even if the theory of evolution were ever to
succeed in furnishing

as satisfactory an explanation of the natural development of the
former as it has of the natural development of the latter, I think that
the truest exponent of the meaning—as distinguished from the
causation—of these higher instincts would still be, not the man of
science, but the poet. Here, therefore, it seems to me, that men of
science ought to leave the question of pain in Nature to be answered,
so far as it can be answered, by the general voice of that humanity
which we all share, and which is able to acknowledge that at least its
own allotment of suffering is not an unmitigated evil.

For clouds of sorrow deepness lend,
To change joy's early rays,
And manhood's eyes alone can send
A grief-ennobled gaze.

While to that gaze alone
expand
Those skies of fullest thought,
Beneath whose star-lit vault we stand,
Lone, wondering, and untaught.

We look before and
after,
And pine for what is not,
Our sincerest
laughter
With some pain is fraught.